Putin is an opportunist. He knows NATO is a paper tiger, the EU nations have disarmed to the point where they can only police their own individual states (or occupy high level staff positions in war zones to give the appearance of an alliance).
Putin knows the US military has been gutted as starting next fiscal year the US Army will be as small as pre- WWII force structure, yet global commitments are not decreasing.
Putin knows Obama is a weak CinC.
All the makings for an autocrat to start war and expand his buffer zones to the former USSR.
I mean, if you were in Putin's position and you were Putin why not take on the West when who goes to the bathroom and where is more important to federal and state governments (no matter what side of that issue one is on) than national security. If Putin does not take on the West this summer I would be surprised. He would much rather face a weak Obama admin than Trump or even Hillary. Hillary might just take out her 'man hate' for her husband on Putin. Trump may nuke Ukraine so Putin can't have it.
Putin has options and they are all from now until the fall 2016. If he does not act I would be surprised.